Dendritic cells and the immunopathogenesis of idiopathic inflammatory myopathies

Purpose of review: Mechanisms driving the autoimmune process in idiopathic inflammatory myopathies (IIMs) have not been unraveled, despite extensive studies. In recent times, it has become apparent that heterogeneous populations of dendritic cells have specialized roles in IIM. Here, we will discuss the role of dendritic cells in the induction of adaptive immune response in HM and review the recent literature addressing the role of dendritic cells in the cause and pathogenesis of inflammatory myopathies. Recent findings: Different subsets of immature and mature dendritic cells have been recently identified in skeletal muscle in IIM. Dendritic cells present in inclusion body myositis and polymyositis are primarily myeloid dendritic cells. In contrast, plasmacytoid dendritic cells, a subset of dendritic cells and considered the main source of the interferon-α/β (IFN-α/β), have been found abundantly in muscle tissue of adult dermatomyositis and juvenile dermatomyositis. Summary: Dendritic cells are associated with the chronic infiltration of mononuclear cells in the inflammatory muscle tissue of HM patients. Increasing evidences point out that dendritic cells are not only crucially involved in the initiation of anti-self immune response but are also essential for the maintenance of autoimmune lesions in inflammatory myopathies.